Pneumatic door-check



(No Model.) J. A. SHERMAN.

PNEUMATIC DOOR UHBUK- No. 298,788. Patented May 20. 1884.

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PNEUMATIC DOOR-CHECK.

SPECIFICATION forming part of Letters Patent No. 298,788, dated May 20, 1884.

Application filed August 13, 1883. (N0 model.)

i'o all whom it may concern Be it known that I, JOHN A? SHERMAN, of Boston, county of Suffolk, State of Massachusetts, have invented an Improvement in Automatic Door-Checks, of which the following description, in connection the accompanying drawing, is a specification, like letters on the drawing representing like parts.

My invention relates to door-checks of that class in which the door is closed by the action of a spring regulated by a cylinder and piston, which acts to produce an air-cushion, preventing slamming of the door when closed.

In another application filed by me I have shown the cylinder pivoted near one end upon a pivot-plate adapted to be attached to the door and the piston-rod passing out through the opposite end 'of the said cylinder, and provided with a backwardly-extended continuation pivoted upon the pivot-plate near the pivotal point of the cylinder.' The said piston-rod is connected by a connecting-bar with the door-frame.

The present invention consists in a cylinder pivoted at one side of one end upon a pivot plate, and having attached .to its other end a connecting-bar, combined with a piston having a piston-rod extending toward the pivoted end of the cylinder and itself connected with the said pivot-plate.

The invention also consists in details of construction of parts hereinafter described.

The drawing shows in plan view and partly in section a door-check embodying this invention, the parts being shown in dotted lines in the position assumed when the door is partially opened.

The cylinder a, piston Z1 therein, and actuating-spring c are or may be substantially the same as in door-checks already in use, and do not need to be further described. The said piston and cylinder entrap air, by which the force of the actuating-spring and operation of the apparatus are modified and regulated to prevent the slamming of the door. The head 6 of the cylinder a is provided with a lug, f, at one side thereof, by which it is pivoted upon a pivot-plate, h, adapted to be securely fixed upon the door or doonframe. The piston b is normally held by the spring c near thehead g of the cylinder, remote from the door, and the piston-r0d iextends toward the pivoted I head a of the cylinder, and is itself pivoted at m upon a lug, h, of the pivot-plate h, the said lug projecting a considerable distance from the plate and theend of the cylinder a, the head e of which has an inwardly-projecting recess or pocket, 6, to receive the said lug when the parts are in the normal position shown in full lines. It will be seen that when the cylinder is turned in the direction of the arrow 2 on its pivot f the piston b will be moved in the cylinder away from the head g, compressing the actuatingspring c, and the force of the said spring will tend to move the piston back, and thus turn the cylinder on its pivot f in the direction opposite the said arrow. The cylinder is caused to thus turn on its pivot and compress the spring as the door is opened by means of the connecting-bar 0, pivoted at one end of the cylinder-head g, or a suitable stud, g, fixed thereon, and at its other end to. the door-frame, in such position with relation to the hinge of the door and pivotal point of the cylinder that as the door is turned on its hinge the said cylinder is rocked on its pivot and the piston-rod t drawn outward from the end thereof, as shown by the dotted lines in the drawing. The lug h is extended into the cylinder, as shown, so that the line of movement of the connected end of the piston-rod 2 which is in an are about the point f as a center, will be more nearly in line of the axis of the cylinder than it would be if the said pointm were as near to the plate h as the pivotal point f.

The recessed portion of the cylinder-head e is slotted, as shown at 3, to permit the lateral movement of the piston-rod as it moves in the curved path with relation to the axis of the cylinder, and the piston is provided with a leather or other flexible packing, enabling the slight rocking movement to take place without detriment to the operation of the apparatus.

If necessary, the piston-rod 1' may be made with a pivotal joint, preferably at the point where it is connected with the piston, so that the latter will not be caused to rock at all in the cylinder.

The piston b is provided with the usual valve, m, to permit air to enter between it and the cylinder-head g as the piston moves away therefrom, and in door-checks as usually constructed the head of the cylinder toward which the piston moves under the action of the spring is provided with a small'orifice and a regulating-screw to control the escape of the air, and thus regulate its cushioning effect. In this construction it sometimes happens, when the apparatus is used upon a door at the outside of a building, in rainy weather, water will enter the said orifice, interfering with the action of the apparatus. In order, to obviate this difficulty, the regulating-screw 0 is in the 'present'invention placed in the piston, and in order to afford access to it the cylinder-head g is provided with an opening of sufficient size to admit the end of a screw-driver, the said opening being itself closed by a light removable plug or stopper, 1).

In this apparatus, when the door is opened wide, so as tobring the pivotal point 9 nearly in line between the pivotal point f and pivotal point 0 of the bar 0, the apparatus is at a dead-center as far as the force of the spring 0 is concerned. In order to overcome the deadcenter, an auxiliary spring, r, is employed pressing on the bar 0 beyond the pivotal point 9, it being brought into operation when the said bar 0 is nearly in line with the axis of the cylinder.

I claiin '1. The cylinder and its pivot-plate, combined with the'piston and its piston-rod extending toward and pivotally connected with the said pivot-plate, and the connecting-bar pivotally connected with the end of the cylinder opposite the pivot-plate, substantially as described.

2. In a door-check, the cylinder, piston, piston-rod, and actuating-spring, combined with the connecting-bar and auxiliary spring coo-operating therewith, substantially as described.

3. In a door-check, the cylinder and piston, provided with a valve and an orifice and connecting mechanism between them and the door, combined with the regulating-screw controlling the orifice in the said piston and wholly inclosed in the interior of the piston, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

JOHN A. SHERMAN.

WVitnesses:

Jos. I LIVERMORE, V. H. SIGSTON. 

